How long is my menstrual cycle?

How do I count the days of my menstrual cycle? Do I start counting the day I start bleeding or when I finish?

Your cycle begins on the first day you have regular bleeding. Spotting doesn’t count. For example, Cycle Day 1 is the first day of your period; Cycle Day 2 is the second day of your period, Cycle Day 3 is the third day of your menstrual flow, and so forth.

As an example, create sample menstrual calendar for the month of January. Let’s say you had spotting on January 3rd, but you didn’t have regular bleeding until the next day. The first day of your menstrual period would be January 4th. The first day of your period is also called “Cycle Day 1”.

Now, create sample menstrual calendar for the month of February. Let’s pretend your period started on the 2nd. In January, your period started on Jan. 4th and in February it started on the 2nd.

When your health care provider asks you: “When was your last period?” The answer is the date of the first day of your last period (not the day it ended). Ex.= February 2nd.

To figure out how long your cycle is, start at cycle day 1 of your last menstrual cycle and begin counting (Cycle day 1,2,3,4 and so forth). The length= the last cycle day before you started bleeding again. For example – According to the January and February calendars, the cycle length would be 28 days, meaning your period comes on average, every 28 days. However, keep in mind that your cycle may vary in length.

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The Center for Young Women’s Health (CYWH) is a collaboration between the Division of Adolescent and Young Adult Medicine and the Division of Gynecology at Boston Children’s
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